Twist tester



H. J. CARTER TWIST TESTER April 16 2 Sheets-Sheet 1 Filed May 2'7. 1966m m v w E mm 5% 3 mm ON mm H. J. CARTER TWIST TESTER 2 Sheets-Sheet 2Filed May 27. 1966 mmoom United States Patent 3,377,853 TWIST TESTERHarry J. Carter, Wilmington, DeL, assignor to FMC Corporation,Philadelphia, Pa., a corporation of Delaware Filed May 27, 1966, Ser.No. 553,367 6 Claims. (Cl. 73-160) The present invention relates to anapparatus for ascertainin g the number of turns per inch or other unitof length in a twisted strand, particularly a strand of yarn, and moreespecially to an apparatus for determining without the intervention of ahuman operator the amount of twist at spaced distances along the lengthof a strand whereby the average amount of twist along the length of thestrand may be accurately ascertained.

The amount of twist affects the strength, coefficient of friction, dyeabsorption, and other characteristics of a yarn, as well as the hand orfeel of the fabric made of the yarn. It is therefore important for thethrowster or yarn manufacturer to know exactly how much twist is beinginserted and for the fabricator to know the amount of twist in the yarnbeing used for weaving or knitting the fabric. Since the amount of twistinserted into a yarn depends upon the speed of the twisting device andthe speed with which the yarn is passed through the twisting device, itis theoretically possible to know the amount of twist, but in practiceone or both speeds may vary from the intended speed. It is thereforedesirable to be able to ascertain accurately the actual amount of twistin a given strand or a strand from a particular production run.

Prior to the present invention, the amount of twist in a yarn wasascertained by cutting a specimen length of yarn and clamping it atpoints a known distance apart.

One of the clamps was then rotated to take the twist out of the yarnwhile the other clamp was urged to move away from the rotated clamp asthe yarn elongated due to the removal of twist. This twisting wascontinued until the yarn was twisted in the opposite directionsufficiently to restore the other clamp to its original position. Acounter was provided for indicating the number of revolutions of therotated clamp and by dividing the total number of revolutions by afactor of two (half of the revolutions being effective to untwist thespecimen and the other half re inserting the twist but in the oppositedirection) and then dividing by the number of inches between the clamps,the number of turns of twist per inch of length was ascertained. Anapparatus similar to those normally used for this operation is describedin US. Patent No. 1,928,271. In use, this prior art apparatus is slowand tedious in that it requires the constant attention of an operatorand the indicated results are also dependent at least to some degreeupon the operator.

It is an object of the present invention to provide a yarn twist testerwhich, once the yarn has been threaded therethrough, will indicate theamount of twist without further attention by a human operator.

It is a further object of the invention to provide a yarn twist testercapable of performing a test at spaced points along a continuous lengthof yarn whereby the average twist along the yarn may be ascertained.

A further object of the invention is to provide an appar-atus which maybe used for testing for the amount of twist at spaced points along ayarn strand and wherein the twist in the yarn is the same after testingas before.

Other and further objects, features, and advantages of the inventionwill become apparent as the description of a preferred embodimentthereof proceeds.

Referring now to the drawings:

FIG. 1 is a diagrammatic side elevational view of the apparatus;

Cal

"ice

FIG. 2 is an enlarged fragmentary sectional View of one of the yarnclamps; and

FIG. 3 is a wiring diagram.

The apparatus comprises a pendulum 10 secured to a shaft 12 pivotallymounted between a pair of uprights 14, only one of which is shown inFIG. 1. An arm 16 is secured to shaft 12 and carried on its free end areselective weights 18 by means of which the pendulum is urged to swing ina counterclockwise direction. For convenience in lacing the apparatus, asuitable stop 20 secured to the end of an arm 22 adjustably connected toone of the uprights 14 may be provided for limiting the counterclockwisemovement of the pendulum. Conveniently, the pendulum may take the formof a tube having a plug 24 in the lower end thereof and another plug 26located above the lower end of the tube. A slot 28 is provided in thetube just below plug 26 and slidably mounted within the tube is ayarn-gripping member 30, which is urged by a spring 32 to engage plug 26so as to grip the yarn as will presently be explained. Secured toyarn-gripping member and extending through an opening in plug 24 is arod 34 having an enlarged lower end 36. A downward pull on rod 34disengages member 30 from plug 26 so that a yarn strand may be lacedthrough the slot 28.

A rotatably mounted element 38 is provided with a pair of yarn-grippingjaws 40 and 42 carried by and urged together by spring members 41 and43. Carried at the end of a hollow shaft 44 is a tapered jaw-operatingmember 46. Shaft 44 is slidable longitudinally within element 38, but iskeyed thereto so as to rotate therewith. Secured to or formed as a partof element 38 is a pulley 48 by means of which said element may berotated. The hollow shaft extends entirely through element 38 and thepulley 48 and on its outer end is provided with a collar 50 betweenwhich and a shoulder of pulley 48 is a spring 52 bymeans of which shaft44 is urged toward the left, as viewed in FIG. 1 to position taperedjaw-operating member 46 so that the spring-pressed jaws 40 and 42 mayclose upon and grip a yarn strand extending therebetween. A shaft 54rotatable about a vertical axis is mounted in the vicinity of collar 50and an arm 56 is secured to the upper end of said shaft and has a freeend located closely adjacent collar 50 and secured to the lower end ofshaft 54 is an arm 58 connected by a link 60 to the armature of apull-type solenoid 62. The rotatable shaft 54 and the parts connectedthereto are shown diagrammatically in both FIGS. 1 and 3.

The yarn to be tested is indicated at 64 and in initially lacing up theapparatus the yarn is manually drawn from a supply, not shown, andthreaded first through a suitable guide 66. The operator then manuallyreleases the gripping member 30 by pulling down on rod 34 and threadsthe yarn through the slot 28 of the pendulum. An ample supply of yarn ispulled through slot 28 and the operator then releases the rod 34 so thatthe yarn is gripped to the pendulum. The operator then presses on collar50 to open jaws 40 and 42 and threads the yarn between the jaws andthrough the hollow shaft 44 and between a set of rubber-covered feedrolls 68 and 70. When the operator releases collar 50, the yarn isgripped to the rotatablymounted element 38 through the spring-pressedjaws 40 and 42.

Feed roll 68 is secured directly to the shaft of an electric motor 72 ormay be connected to the motor through a speed reduction unit. Roll isfreely rotatable upon a shaft 74 carried by an arm 76 which is pivotallymounted at 78 on a fixed support. A spring 80 extending between one endof arm 76 and a fixed anchor normally holds roll 70 out of engagementwith roll 68. Connected through a spring 82 to the end of arm 76opposite from the spring p 80 is the armature of a pull-type solenoid 84and when said solenoid is energized, as will presently be explained,roll 70 is moved toward roll 68 so as to pinch the yarn therebetween,whereby when motor 72 is activated, the yarn will be drawn through theapparatus. A counter 86 is connected to shaft 74 so as to indicate thenumber of times that roll 70 is raised.

Before detailing the means for accomplishing the same, the manner ofoperation in performing a test will be briefly explained, it beingassumed that the yarn is laced through the apparatus. The means grippingthe yarn to the pendulum and the means gripping the yarn to therotatable element 38 are both released; that is, they are released fromengagement with the yarn. Solenoid 84 is energized so that the yarn isgripped between feed rolls 68 and 70 and motor 72 is staited to causethe yarn to be pulled through the apparatus. After a predeterminedlength of yarn has been pulled through, motor 72 is stopped but solenoid84 remains energized so that the yarn is gripped between the feed rolls.The yarn is then gripped to the pendulum which at that time has beenswung by the weights 18 to the position shown in FIG. 1. Located betweenfeed rolls 68 and 70 and the rotatable element 38 is an arm 88, one endof which is operatively connected to a clock motor 90. Arm 88 isnormally held down by a spring 92 but immediately after the yarn becomesgripped to the pendulum, clock motor is started and this swings the freeend of arm 88 in an upward path which brings the arm into engagementwith the yarn so as to tension the yarn between the feed rolls and thependulum. This tension causes the pendulum to swing in a clockwisedirection and when the yarn-gripping portion of the pendulum reaches apredetermined position (referred to hereafter as a home position), clockmotor 90 is stopped and solenoids 62 and 84 are deenergized. This causesthe yarn to become gripped to the rotatable element 38 and released fromthe feed rolls. The element 38 is then caused to rotate in a directionwhich first untwists the yarn so that the pendulum 10 may swing awayfrom its home position as the yarn elongates due to the removal of thetwist, and the rotation of element 38 is continued until an equal amountof twist is inserted into the yarn in the opposite direction so as torestore the pendulum to its home position. When the pendulum is restoredto its home position, it causes activation of means which reverses therotation of element 38 and the yarn is again untwisted and retwisteduntil the pendulum again moves away from and is restored to its homeposition. Due to the double untwisting and retwisting, the yarn now hasits original twist, and this second time that the pendulum is restoredto its home position it causes the whole cycle described above to berepeated.

Rotatable element 38 is provided with a shoulder 94 which operates aswitch 96, which in turn causes one to be added to a counter 98 for eachrevolution of element 38. Over a period of time the counter 86 indicatesthe number of tests performed, since this counter is operated every timethe feed roll 70 is raised against feed roll 68 to cause the yarn to bedrawn through the apparatus. The average twist per inch of yarn iscomputed by dividing the total number of revolutions of element 38asindicated by counter 98 by a factor of two (since there are twotwisting operations per test) and then dividing by the number of testsas indicated by counter 86 and by the distance between the jaws 40 and42 of element 38 and the gripping elements 26 and 30 of the pendulumwhen the pendulum is in its home position. Conveniently, thelast-mentioned distance may be ten inches.

After the initial lacing-up, the periodic release of the yarn from thegrip of the pendulum is accomplished by a solenoid 100 which, whenenergized, pushes down on a lever 102 which is-pivotally mounted at 104and is provided with a bifurcated end which overlies the enlarged lowerend 36 of rod 34. A spring 106 normally holds lever 102 out ofengagement with the end 36 of rod 34 and with the lever free ofengagement with the end of 34, rod 36 is free to swing within thebifurcated end of the lever.

Rotatable element 38 is driven by a reversible electric motor 188 (seeFIG. 3) through a belt 110 engaged with the pulley 48 and with a pulley112 on the shaft of the motor.

Referring now to FIG. 3, the testing operation is begun by closing aswitch 114 in a line 116 so as to energize a polarized light source 118connected to an alternating current power line 126* and 122 through theline 116 and a line 124. Light source 118 is directed toward a lightsensitive cell 126 and when light strikes the cell a circuit isestablished to the coil of a relay R through line 128 from the powerline 120, line 130 from the cell to the relay coil and line 132 from therelay coil to power line 122. Light source 118 and cell 126 are mountedon opposite sides of pendulum 10 above the pendulum supporting shaft 12.The pendulum extends above shaft 12 and carries on this upper extensiona shield 134 (see FIG. 1) having therethrough a small opening 136. Lightfrom source 118 is permitted to strike the sensitive part of cell 126only by passing through the opening 136 and said opening is aligned withthe cell only when the pendulum is in its home position.

After closing switch 114, the operator closes a switch 135 in a line 136to establish a circuit to a clock motor 148 through the line 136 frompower line 120 and a line 142 to the power line 122. From this point on,no further attention by the operator is required until the counter 86indicates that the desired number of tests have been run. If desired,the aparatus may very easily be arranged to automatically stop after apreselected number of tests, but mechanism for doing this has not beenshown.

Motor drives a shaft 144 which carries a series of cams arranged tooperate a series of switches A, B, C, D, E, and F and shortly after theshaft starts to turn, switches D and F are closed. One side of switch Fis connected to power line 128 and the other side is connected through alead 146 to solenoid 106 which in turn is connected through a lead 148to the power line 122.. Thus closing switch F energizes solenoid 180which disengages the pendulum 18 from the yarn as previously explained.One side of switch D is connected to power line 120 and the other sideis connected through a line 150 to a contact bar 152 of a normallyclosed relay R Through the contact bar 152, line 150 is connected to aline 154 which leads to solenoid '62 which in turn is connected to powerline 122 through a line 156. Thus closing, switch D energizes solenoid62 to cause the yarn to be released from the grip of rotatable element38 as aforesaid.

As the cam shaft 144 continues to rotate, switches C and E are closed.One side of switch C is connected to power line 120 and the other sideof said switch is connected through a line 158 to solenoid 84 which inturn is connected through a line 160 to power line 122. Thus closing,switch C energizes solenoid 84 to cause feed roll 70 to pinch the yarnstrand between it and feed roll 68 as aforesaid. One side of switch E isconnected to power line 120 and the other side of this switch isconnected to motor 72 through a lead 162 and the motor is connectedthrough a lead 164 to power line 122. Thus closing of switch E iseffective to start motor 72 whereby the yarn strand is drawn through thependulum gripper and through the rotatable element 38 until a freshportion of yarn extends between the pendulum and element 38. At thistime the cam shaft 144 has rotated to a position to open switch E,whereupon motor 72 stops and no further yarn is drawn through.

Right after switch E is opened, switch F is permitted to open to breakthe circuit to solenoid 100, whereupon the yarn becomes gripped to thependulum as previously explained. Immediately after switch F opens, acam on shaft 144 closes switch A, one side of which is connected topower line 120 and the other side of which is connected by a line line166 to a second switch bar 168 of the normally closed relay R The otherend of bar 168 is in contact with a line 170 leading to clock motor 90which is connected to the power line 122 through a lead 172. Thus acircuit is established to motor 90 and said motor starts to run to causetensioning of the yarn strand whereupon pendulum is swung in a clockwisedirection until it reaches its home position wherein light from thesource 118 is permitted to strike the light sensitive cell 126 aspreviously explained.

Activation of light sensitive cell 126 closes the circuit to the coil ofnormally open relay R as aforesaid to close the contacts of said relay.One of the relay contacts is connected to power line 120 through a lead174 and the other contact is connected to the coil of a stepping switch176 through a lead 178. The coil of switch 176 is also connected topower line 122 through a lead 180 and thus closing relay R is effectiveto activate the stepping switch. The stepping switch has a common lead182 connected to power line 122 and a stepping contact engageable withany one of three contacts 184, 186, 188. Upon this first describedclosing of relay R the stepping contact of switch 176 moves out ofengagement with contact 184 with which it is normally engaged and intoengagement with contact 186 to establish a circuit to the coil of relayR through a line 190 leading from the contact 186 to the relay coil anda line 192 leading from the relay coil to the power line 120.Energization of the coil of relay R opens both sets of contacts of thisnormally closed relay and this simultaneously deenergizes solenoid 62 tocause the yarn strand to become gripped to the rotatable element 38 andstops clock motor 90, both as previously explained.

As cam shaft 144 continues its rotation a cam thereon becomes effectiveto permit switch C to open thus breaking the circuit to solenoid 84 andfreeing the yarn from the grip of feed rolls 68 and 70. A slight furtherrotation of cam shaft 144 closes switch B, one side of which isconnected to power line 120 and the other side of which is connectedthrough a lead 194 to one of the contacts of a normally closed relay RThe other contact of relay R is connected through a lead 196 and afull-wave bridge rectifier 197 to one of the two input contacts of amanually operated double pole double throw reversing switch 198 theother input contact of which is connected to power line 122 throughrectifier 197 and a line 200. The two output contacts of switch 198are'connected to the input contacts of a solenoid operated reversingswitch 202 the output contacts of which are connected to the reversiblemotor 108.

At this time it will be mentioned that yarn is sometimes twisted in onedirection known as S twist and sometimes in the opposite direction knownas Z twist. Since in performing a test the first operation is to removethe twist, the operator must examine the yarn to ascertain the directionof the twist. Having determined this, the manually operated reversingswitch 198 is conditioned so that the current passing through thisswitch and through switch 202 when the latter is in its normal attitudeis effective to drive the motor 108 in the direction to remove the twistfrom the yarn. Thus, with switch 198 properly conditioned before orright after the yarn is laced through the apparatus, closing of switch Bis effective to start motor 108 to run in the direction to remove twistfrom the yarn.

As the twist is removed from the yarn, pendulum 10 swings away from itshome position whereby light sensitive cell 126 and relay R aredeenergized. When all of the original twist is removed from the yarn,rotatable element 38 continues to be rotated by motor 108 in the samedirection whereby reverse twist is inserted into the yarn. When theamount of reverse twist becomes the same as the amount of originaltwist, pendulum 10 will have been returned to its home position to againcause activation of relay R whereupon the stepping contact of steppingswitch 176 is moved out of engagement with contact 186 and intoengagement with contact 188.

Engagement of the stepping contact of switch 176 with the contact 188establishes a circuit to the coil of a solenoid 204 which controlsreversing switch 202. The circuit is established through a line 206leading from contact 188 to the solenoid coil and a line 208 leadingfrom the coil to power line 120. When the solenoid 204 is thus energizedit reverses switch 202 which in turn reverses the rotation of motor 108and rotatable element 38. R0- tatable element 38 then removes thereverse twist from the yarn and continues to rotate until the originaltwist is restored to the yarn. During this rotation of element 38,pendulum 10 swings away from its home position and returns to the homeposition. Upon this return of the pendulum, relay R activates steppingswitch 176 to swing the stepping contact thereof out of contact withcontact 188 and into contact with the contact 184, thus breaking thecircuit to solenoid 204 whereupon reversing switch 202 becomesconditioned as it was originally and at the same time establishing acircuit to the normally closed relay R through a line 210 leading fromcontact 184 to the relay coil and a line 212 leading from the relay coilto power line 122. When relay R is activated it breaks the circuit toline 196 leading to the switch 198 and thereby stops motor 108. Thetotal number of revolutions of element 38 during this test is recordedon counter 98. As the cam shaft 144 continues to turn theabove-described cycle is repeated and these cycles continue until theoperator opens switch after observing from counter 86 that the desirednumber of tests have been run or after an automatic control shuts theapparatus oif.

Having thus described a preferred embodiment of the invention, what isclaimed is:

1. Yarn twist testing apparatus comprising a rotatably mounted yarngripping element adapted to have a yarn strand extended therethrough,resilient means for closing said gripping element so as to grip the yarnstrand, a first releasing means for opening said gripping element sothat the yarn strand may be pulled therethrough, yarn gripping meanshaving a home position located at a preselected distance from said yarngripping element, resilient means for closing said gripping means so asto grip a yarn strand, a second releasing means for opening saidgripping means so that the yarn strand may be pulled therethrough, meansurging said yarn gripping means in a direction away from said yarngripping element, drive means for rotating said rotatably mounted yarngripping element about an axis coincident with the axis of the yarn, andyarn take-up means for pulling the yarn strand through the grippingelement and the gripping means when they have been released from theyarn by said first and second releasing means.

2. The apapratus set forth in claim 1 comprising means for activatingsaid first and second releasing means whereby the rotatable yarngripping element and the yarn gripping means are released from the yarnstrand, and means operable upon said activation of said first and secondreleasing means for activating said yarn take-up means to pull the yarnstrand through said rotatable yarn gripping element and said yarngripping means.

3. The apparatus set forth in claim 2 comprising means for deactivatingsaid second releasing means whereby said yarn gripping means becomesgripped to the yarn strand, and tensioning means for tensioning the yarnstrand to draw said yarn gripping means to its home position against theaction of the means urging said yarn gripping means in a direction awayfrom said yarn gripping element, said tensioning means drawing the yarnstrand through said yarn gripping element during the tensioning.

4. The apparatus set forth in claim 3 comprising means activated whensaid gripping means reache said home position to deactivate said firstreleasing means and start said drive means whereby said rotatable yarngripping element is gripped to the yarn strand and rotated in thedirection to remove the twist from the yarn strand.

5. The apparatus set forth in claim 1 comprising sequentially operated,(1) means for activating said first and second releasing means wherebythe rotatable yarn gripping element and the yarn gripping means arereleased from the yarn, (2) means for operating said yarn take-up meansto draw the yarn through the yarn gripping element and the yarn grippingmeans, (3) means for deactivating said second releasing means wherebysaid gripping means grips the yarn strand, (4) means for tensioning theyarn strand to draw the yarn gripping means to said home position, (5)means for deactivating said first releasing means whereby said grippingelement grips, the yarn strand, and (6) means for rotating saidrotatably mounted yarn gripping element to remove the twist from 8 theyarn strand and insert an equal amount of opposite twist into thestrand.

6. The apparatus set forth in claim 5 comprising means for recording thenumber of rotations of said rotatably mounted yarn gripping element andmeans for recording the number of operations of said yarn take-up means.

References Cited UNITED STATES PATENTS 1,928,271 9/1933 Smith 73-1582,037,274 4/1936 Scott 73-158 2,590,398 3/1952 Geganschatz 7395.5

LOUIS R. PRINCE, Primary Examiner. J. NOLTON, Assistant Examiner.

1. YARN TWIST TESTING APPARATUS COMPRISING A ROTATABLY MOUNTED YARNGRIPPING ELEMENT ADAPTED TO HAVE A YARN STRAND EXTENDED THERETHROUGH,RESILIENT MEANS FOR CLOSING SAID GRIPPING ELEMENT SO AS TO GRIP THE YARNSTRAND, A FIRST RELEASING MEANS FOR OPENING SAID GRIPPING ELEMENT SOTHAT THE YARN STRAND MAY BE PULLED THERETHROUGH, YARN GRIPPING MEANSHAVING A HOME POSITION LOCATED AT A PRESELECTED DISTANCE FROM SAID YARNGRIPPING ELEMENT, RESILIENT MEANS FOR CLOSING SAID GRIPPING MEANS SO ASTO GRIP A YARN STRAND, A SECOND RELEASING MEANS FOR OPENING SAIDGRIPPING MEANS SO THAT THE YARN STRAND MAY BE PULLED THERETHROUGH, MEANSURGING SAID YARN GRIPPING MEANS IN